Oscillation-responsive device.



PATENTED JUNE 26., 1906.

L. DE-FO EST.

OSCILLATION RESPONSIVE DEVIGB.

APPLICATION FILED JAN. 18. 1906.

2 SHEETS-SHEET 1.

No. 8 4,637? 1 PATENTED JUNE 26,-1906.

L. 135 FOREST. I OSGILLATIQN RESPONSIVE nsvmn.

APPLIGATION FILED JAN. 13. 1906.

. 2 SHEETS-rSHI-IET 2 wowe UNITED STATES PATENT OFFICE.

LEE DE FOREST, or NEW YORK, N.- Y.

OSClLLATlON-RESPONSIVE DEVICE.

Specification of Letters Patent.

Patented June 26, 1906.

Application filed January 18, 1906. Serial No. 296,615.

- sive Devices, of which the following is a specification.

My invention relates to devices for de tecting feeble electrical currents or oscilla tions in general, and especially such currents or-oscillations which are developed in wireless-telegraph receiving systems.

The object of my invention is to provide an oscillation detector or responder of reat simplicity and sensitiveness and one w ich, inasmuch as it does not depend for its operation u on any variation of resistance of an imper ect electrical contact or any variation of the apparent resistance or counter electromotive force of a polarization-cell, requires no adjustment when employed for receiving wireless-telegra h signals.

With these 0 jects in view my invention comprises a receptacle inclosing a sensitive gaseous conducting medium, the conductivity'of which does not necessarily depend upon the heat of combustion, althou h such conductivity may be increased by Iieating said gaseous medium, and which in some cases requires practically no heating at all, a wave-intercepting means associated with said gaseous conducting medium, whereby the feeble, electrical currents or oscillations resulting from the energy absorbed from electromagnetic signal waves may be impressed u on said gaseous conductin medium to a ter its conductivity, and a signalindicating device operativly connected with said gaseousconducting medium, whereby alterations in the conductivity of the latter may be made manifest.

My invention may best be understood by having reference to the drawings which accompany and form a part of this specification and which illustrate diagrammaticall several simple and effective means where y my invention may be practiced.

In the drawings, Fi ures 1, 2, 3, 4, 5, and 6 represent wireless te egraph receivin systems provided with vvarious forms of t e oscillation responsive device which forms the subject-matter of the present invention.

In each figure, Arepresents a receiving antennaconnected to earth at E and associated with the receptacle B. In Figs. 1, 3, 4, 5,

and 6 the sensitive aseous conducting medium inclosed in said receptacle is shown interposed between the antennae and their earth connections, while in Fig. 2 said medium is shown interposed between the terminals of the tuned receiving-circuit i C G i H,

which is inductively associated, by means of i the autotransformer H, with the antenna A. By means of the four adjustable contacts 0', said tuned receiving-circuit and antenna may each be attuned to the frequency of the waves to be received. My invention, however, is not limited to any particular wirelesstelegraph system, nor is it limited to wireless telegraphy, for it may be employed as a detector of feeble electricalimpulses however produced.

I have discovered that the gaseous me-v dium intervening between two separated electrodes if put into a condition of molecular activity will become highly sensitive to electrical oscillations, so that the assage across such-medium of said oscillatlons will alter the conductivity thereof, and thereby create current variations in a circuit including said electrodes. The means which may be employed for putting said gaseousv medium into a condition of molecular activity ma consist of means whereby the medium is eated either by radiation, conduction, or by the actual combustion of gases. An electric cur.- rent from any suitable source may be employed to heatv two highly-resistant electrodes, and thereby to heat the as intervening between said electrodes wit out havin recourse to the'heat of combustion. Sai gas may be air, or the electrodes ma be inclosed and surrounded by an .suita le gas. The heating of the gas-may a so be afiected by radiation from said electrodes. In fact, in the invention disclosed in the'present application any suitable means for producing a heated gas with properly dissociatedand conductin ions ma be employed.

In a l the em odiments of the present invention the electrodes are inclosed and are means, or by any other suitable means; but in those embodiments of my invention shown in Figs. 4, 5 and 6 practically heating at all is required, while if in plac of the potassium or other salt hereinafter described as suitable for use in Fig. 6 some radio-active substance, such as radium bromid, be emplo ed absolutel no heating is necessary.

lhiFig. 1 two laments C, which may be ordinary incandescent-lamp carbon filaments, are sealed into the receptacle B, and each is connected to a separate battery D. The

cal-circuit battery H and telephone F connect said filaments C. One filament is con- 'nected with the antenna A and the other is connected to earth E, although the said filaments may be associated with the antenna in any manner in which existing wireless-telegraph receivers are associated with their receiving antennae. In lieu of connecting the telephone F in series with the local-circuit battery H said telephone may be connected in shunt to the circuit including the filaments C, which form the electrodes of the oscillation responsive device, and local bat: tery H, as shown in Fig. 2, and such arrangement of telephone-receiver maybe employed, if desired, in those embodiments of the present invention which are shown in Figs. 3 to 6, inclusive.

The otential to be impressed upon the electro es C by the battery Hdepends upon the nature of the gas intervening between said electrodes and upon the degree of ex haustion maintained within the rece tacle B. I have found that from twenty-Eve to one hundred and ten volts is sufficient, and by employin a hi her degree of exhaustion a much smal er voItage may be used. The conductivity of the gas, which may be air or a gas containing compounds of the halogens or halogen salts or which may be'mercury vapor, is increased by the heat resulting from the assa e of the current from the bat-- teries D t oug the filaments C, and a leakcurrent of relatively small value continuall flows in the circuit containing the battery 1% and the electrodes 0 across the ga intervening between said electrodes. 'l he passage of electrical oscillations across said gap alters the conductivity of the gas in. said gap, probably by chan ing the speed of the ions in said as, and t ereby current variations are pro uced in the circuit containing the battery H, the electrodes 0, and the tele- %hme F, causing said telephone to respond.

en' the telephone is in series with the battery H and electrodes 0, the passage of oscillations across the gap between the electrodes causes an increase of current through the telephone, and when the telephone is in shunt to said electrodes, as shown in Fig. 2, the .passage of oscillations across the gap causes a diminution of current through the telephone.

It is not necessary to employ two heated electrodes in carrying out my invention, for,- as shown in Fig. 3, one electrode may be regillizfied by a conductor I, herein shown as a] of. platinum or other suitable material.

" tery J in series wit .the te seiner.

In this case the conductivity of the gaseous medium between the two electrodes and O is sufiiciently increased to render the same sensitive to the electrical oscillations by the radiation of heat from the electrode C.

In that embodiment of my invention shown in Fig. 4-1 dispense with both heated electrodes C and substitute therefor two electrodes I, of platinum or other material, and connect the same in circuit with the battery H and telephone F. In Fig. 4 the tele hone F may be connected in shunt to the atter circuit in the manner shown in Fig. 2 of t e present case.

In Fig. 5, L represents a source of alternating electromotive force of a frequency so high that a hi h-pitch note is constantly heard in the telep one F or else so high as to exceed the limit of response of the telephone-diaphragm. The advantage in using the source of alternatin 'electromotive force is that the voltage may e stepped up by a transformer M to any desired amount for example, from fifty to one thousand voltsand impressed upon the electrodes I. In lieu of an alternating-current generator such as shown in Fig. 5 any source of vibrato electromotive force may be employed. T e telephone F may be included in series with the circuit containing the secondary of the transformer M and electrodes I, or it may be connected in shunt to said circuit, as above stated in connection with Fig. 2, and the effect of the passage of high-frequency oscillations across the .gap between the electrodes I may be increased in the tele hone b includin a batlhphone. n such case the conductivity of the gas in said gap effected b the hi h-potential alternating current wil allow t e relatively low potential'direct current fromthe battery J to flow in-the circuit containing the tele hone and the electrodes, and the passage 0 electrical oscillations across the ga between the electrodes will produce sud en chan es in the conductivity ofsaid gas, and there ore in the amplitude of the current flowing in the telephone-circuit.

.. A convenient way of producing a gaseous medium containing compounds of suitable.

salts is shown in Fig. 6, in which a globule of a solution of some such salt is placed in the bottom of a vessel O, as shown at Q, and a heating-coil P is associated with said l obule in such a way that the current from t e battery K will heat said coil and create a heated gas of said salt in the globe O. I prefer to emploiy potassium h drate as the salt to be heats and. better e sets may be obtained by incloaingthe globe 0 inside the evacuated gillobe B to prevent the radiation of heat from t e inner globe. The heated as from the potassium or other salt fills t e lobe O, whichmaybeexhaustedtoan desire degree, and completes the circuit 0 the battery. J

means for sensitizing the interelectrode me dium, as suitable salts impregnating the said medium, as before noted, or means for producin and maintaining the mediumin astate ofmo ecular activity, as by heating, or both means for sensitizing may be concurrently em loyed.

do not wish to be limited to the particular embodiments of my invention which I have herein disclosed, inasmuch as many modifications may be made therein by those skilled in the art Without departing from the spirit of my invention.

I claim 1 1. An oscillation-responsive device comprising a receptacle inclosing a sensitive gase- 0111s conducting medium containing a halogen sa t.

2. An oscillation-responsive device comprising a receptacle inclosing a sensitive gaseous conducting medium containing a halogen salt and means for heating said medium.

3. An oscillation-responsive device comprising a receptacle inclosing a sensitive gase ous conducting mediumcontaining a potas- 1 sium salt.

4. An oscillation-res onsive device comprising a receptacle inc osing a sensitive gasseparated electrodes sealed in sai rece tacle and each forming part of a separate e ectric circuit," a separate source of electric current for each said circuit, and means whereby electrical oscillations may be im ressed upon the gaseous medium lntervemng etween sald electrodes.

8. An oscillation-responsive device comprising a partially-exhausted receptacle contaimng two se arated electrodes, a source of electromotive orce associated with said electrodes, and means whereby a relatively small electric current is caused to flow normally in the circuit including said source of electromotive force, said electrodes and the gaseous medium intervening between the latter.

9. An oscillation-responsive device comprising a partially-exhausted receptacle containing two se' arated electrodes, a source of electromotive orce associated with said electrodes, and electrical means for heating said' cuit including said source of electromotive force, said electrodes and the gaseous medium intervening between the latter.

10. An oscillation-responsive device comprising a rece tacle, two separated electrodes mclosed wit 'u said receptacle and eachio forming part of a separate electric circuit, a source of electric current associated with each said circuit, and means whereby electncal oscillations may be impressed upon thegaseous medium intervening between said elec: trodes. I

11. An oscillation-responsive device comprisinga receptacle inclosing a gaseous medium contaimng a substance the vapor of which is conducting, and electrical means for heating said medium.

12. An oscillation-responsive device com-' prising a receptacle 'inclosin a gaseous medium containing a halogensa t, two separated electrodes inclosed within said receptacle,

and a source of electric current so associated with said electrodes as to render said gaseous medium sensitive to electrical oscillations.

In testimony whereof I have hereunto subscribed my name this 13th day of Janu- M 1906,

.. LEE DEFOREST.

Witnesses:

Lns'rnn TESTUT,

PHILIP FARNSWORTH. 

